1. Field of the Invention
The present invention relates to apparatus and methods of bagging fragile low density particulate materials such as food snacks like potato chips, corn chips, tortilla chips, and the like.
2. Description of the Prior Art
Food snacks are generally bagged utilizing a single continuous thermoplastic sheet, such as a cellophane sheet, which is formed into a tube about a vertical tubular mandrel or former with overlapping longitudinal edges heat sealed together. A pair of adjacent transverse seals are formed across the thermoplastic tube below the former, the lower transverse seal closing the top of a filled bag and the upper transverse seal closing the bottom of a bag to be filled. A weighed quantity of fragile low density particulate product is discharged through the former and falls into the bag to be filled. It is conventional to oscillate the bag wall by means of engagement of the outside of the bag wall with an oscillating piston of an air cylinder or with an oscillating transverse spring during the filling operation to settle the product in the bag to be filled. The sheet material and the thermoplastic tube are advanced and the transverse seals are repeated to close the top of the newly filled bag and the bottom of the next bag to be filled. Bags formed in this manner from single sheets are sometimes referred to as pillow bags or pouches.
U.S. Pat. No. 1,937,501 for machine for making and filling packages and U.S. Pat. No. 1,944,147 for bag making and filling machine disclose pillow bag making apparatus wherein a former or a tubular mandrel coaxially surrounding the feed tube is reciprocated vertically to advance the tubular bag between bag sealing and filling operations.
Generally the prior art apparatuses used in bagging fragile low density particulate product, such as food snacks like potato chips, corn chips, tortilla chips and the like, utilize a single former and have limited speed in bag forming capacity so that the employment of a large number of apparatuses are required for commercial scale production. The mechanism for forming the single sheet into a tube has a relatively large size which prevents the assembly of a plurality of bagging units in a single bagging machine of convenient size for installation in a product line. Furthermore these tube formers of such apparatuses have a small range of size tolerance for a given size of bag and are relatively expensive. While the formers can be changed to produce different bag sizes, such change is time-consuming leading to loss of production where the scale of production does not warrant the expense of separate bagging machines and floor space for each of several bag sizes. The longitudinal overlapping seal produced by heat and pressure between a tube former and a heat sealing die is generally weaker and more subject to failure than a seal formed between opposing dies due to the pressure and seal forming limitations of the tube former structure.
Each bag forming and filling apparatus requires sufficient floor space for the apparatus and associated raw product supply and finished product boxing equipment. Thus the quantity of finished product produced per square area of plant floor space is limited by the speed of the bag making and filling apparatus.
Fluid products such as condiments are packed by apparatuses which form and fill multiple columns of bags. The bags are formed by sealing two thermoplastic sheets or the halves of a folded single thermoplastic sheet together. U.S. Pat. No. 3,846,569 for a method of making a disposable precharged coffee bag, U.S. Pat. No. 4,067,173 for a packaging machine, U.S. Pat. No. 4,768,330 for a bag gripper and spreader for form, fill and seal bagging machine and U.S. Pat. No. 4,845,926 for pouch packaging machine with independent side and cross seals disclose apparatuses of this type for forming and filling bags of ground coffee beans, fine particulate material such as dry noodles, and condiments. Bags produced by this type of apparatus have seals formed on all four sides to form the bags from the thermoplastic sheet or sheets. The existing multiple column bag making and filling apparatus is considered suitable, and has been used, only for forming relatively flat bags which can readily accommodate liquid or very fine particulate product.
An object of the present invention is to construct bag forming and filling apparatus and methods which are more efficient and productive in bagging fragile low density particulate products.
Another object of the invention is to provide multi-column apparatus and methods of bag forming and filling which can bag fragile low density products such as potato chips, corn chips, tortilla chips, and the like.